1. Field of the Invention
The present invention relates to an apparatus for testing the performance of a synthetic aperture radar.
2. Description of the Conventional Art
An imaging radar is a system in which a radar transmits and receives electromagnetic waves through an antenna while relatively moving with respect to a fixed ground target and synthesizes an image based on Doppler information of the ground target. To accurately measure the performance of such an imaging radar, a flight test is essentially needed. If it is possible to sequentially reproduce Doppler components received from the ground target in proportion to an antenna beam width every pulse repetition interval, an azimuth resolution test required for the imaging radar can be performed.
A conventional radar test apparatus performs a ground test, with its role being limited to such function as delaying the relative distance between a ground target and a radar, reproducing RCS, and reproducing platform speed and angular information using a Doppler. Also, the conventional radar test apparatus was problematic in that it is not applicable to a system, such as an imaging radar, having a broad instantaneous bandwidth, and pulse stability, which is required for a high-resolution test, is not taken into account.
Unlike the conventional radar, the imaging radar requires technical differences with the conventional radar test apparatus because it has to synthesize an accurate image of a ground target. Specifically, the test apparatus for the imaging radar requires pulse stability for range and azimuth resolution tests of the imaging radar, the function of reproducing the range curvature between the ground target art the imaging radar, the function of reproducing motion generated during the flight of the imaging radar, and pulse-to-pulse phase modulation characteristics.